How to Set Up a Suction Pool Cleaner with a Dedicated Line

Why a Dedicated Suction Line Matters

Most in-ground pools have two suction paths to the pump: the skimmer for surface debris and a main drain for bottom water. A dedicated suction line is a third path, usually a wall fitting near the bottom that connects directly to the pump. Using this line for a suction-side cleaner keeps the skimmer free to handle leaves and surface oil, and it gives the cleaner a consistent, uninterrupted supply of water.

According to the U.S. Environmental Protection Agency's ENERGY STAR program, filtration requires only half the flow rate of running a pool cleaner. A dedicated line allows you to run the cleaner at its proper flow without forcing the filter to handle that higher speed during routine filtration. This separation is the main reason many pool builders include a dedicated suction line in new construction. For a deeper look at the differences, see our article on skimmer vs. dedicated line.

What a Dedicated Suction Line Includes

A dedicated suction line consists of a wall fitting (also called a suction outlet), a dedicated pipe that runs to the pump, and a valve that controls flow from that line. The wall fitting is typically installed below the waterline on the pool wall and accepts the cleaner hose with a threaded or push-fit connection.

The valve may be a three-way valve that selects between skimmer, main drain, and dedicated line, or it may be a separate shutoff valve per line. Many pools built in the last few decades include a dedicated line as standard equipment, but older pools may only have skimmer and main drain connections. You will also need an appropriate hose adapter if the cleaner's hose does not match the wall fitting's thread size. For more on connection types, see our pool cleaner connection types guide.

Step-by-Step Setup

Follow these steps to get your suction cleaner running on a dedicated line:

• Turn off the pump and allow water to settle.
• Attach the cleaner hose to the wall fitting of the dedicated line. Make sure the connection is snug.
• Submerge the cleaner and hose to fill them with water. This is priming and prevents air locks.
• Open the dedicated line valve fully. If there is a valve that controls the skimmer and main drain, close the skimmer valve completely or leave it slightly open to allow some surface skimming.
• Start the pump. If you have a variable speed pump, run it at a speed that gives the cleaner visible movement but not so fast that the cleaner climbs walls too aggressively or air is drawn in.
• Check the cleaner's movement. It should travel across the floor and up walls without stalling.

Balancing the Flow

Balancing flow means giving the cleaner enough suction to move and pick up debris, while avoiding two problems: too little flow (cleaner sits in one spot) and too much flow (cleaner moves too fast, jumps out of the water, or causes air to be pulled in through the pump lid). The right setting depends on your pump's horsepower, pipe size, and the cleaner's design.

ENERGY STAR notes that filtration requires half the flow rate of a pool cleaner, so if your pump runs at a higher speed during cleaning, consider using a variable speed pump to slow down during filtration cycles. Use the cleaner's manual as a starting point, then adjust valve positions and pump speed in small increments. Watch for the cleaner's wheels turning at a steady pace and for the hose to stay free of air pockets.

For more on how flow rate affects cleaner performance, read pool cleaner flow rate explained and our article on pump horsepower requirements.

Common Setup Mistakes

Many first‑time users make mistakes that reduce cleaning performance. Here are a few to avoid:

• Leaving the skimmer valve fully open, which steals flow from the cleaner.
• Not filling the hose with water before starting, causing air locks.
• Running the pump too fast, making the cleaner climb too high and flip.
• Forgetting to close the main drain, causing the cleaner to lose suction.
• Using a hose that is too long or has leaks, reducing suction at the cleaner.

When a Dedicated Line Is Not Available

If your pool lacks a dedicated suction line, you can still run a suction-side cleaner using a skimmer plate adapter that allows the cleaner hose to plug into the skimmer. However, this competes with surface skimming and may require careful valve adjustments. Another option is a robotic cleaner, which is independent of the pool pump and filtration system. Robotic cleaners are powered by low-voltage electricity and have their own built-in filter, so they don't affect the pump flow at all.

If you're weighing your options, see our best suction-side pool cleaners or best robotic pool cleaners for a comparison. You can also read about the difference between robotic vs suction vs pressure cleaners to decide which type fits your pool.

What to pick for your setup

Questions

Do I need to close the skimmer completely when using a dedicated line?

You can close it completely if you want maximum suction to the cleaner, but it's often better to leave it slightly open (about 10–20%) to continue surface skimming. The exact setting depends on your pump's flow and the cleaner's requirements. Start with the skimmer closed, then gradually open it until the cleaner still moves well.

How do I know if my pump has enough flow for a dedicated suction cleaner?

Check the cleaner's manual for a recommended flow rate (usually in gallons per minute). If your pump doesn't have a flow meter, use a simple rule: the cleaner should move at a steady pace and not stall. If it stalls, open the dedicated line valve and close other valves; if it moves too fast, slow it down.

What if my pool doesn't have a dedicated suction line?

You can use a skimmer plate adapter to connect the cleaner to the skimmer. This works but reduces surface skimming while the cleaner runs. A robotic cleaner is another option because it runs independently of the pump.

How do I prime the hose before attaching it to the dedicated line?

Submerge the entire hose and cleaner in the water to fill them with water, then plug the hose into the wall fitting while still underwater if possible. This prevents air locks and ensures the cleaner starts moving immediately.

Can I run the pump on a low speed with a suction cleaner?

Usually not. Suction cleaners need enough flow to move. ENERGY STAR notes that filtration requires half the flow rate of a pool cleaner, so you'll likely need a higher speed for cleaning. A variable speed pump lets you set a high speed for cleaning and a lower speed for filtration.